Eagle County Building Code Energy Modeling & Upfront Cost Analysis

In 2022, Lotus supported Eagle County in analyzing new construction code packages with electrification amendments to provide energy use and cost data which will be used to inform the County code update process in 2023. Lotus analyzed four code package options as they compare to Eagle County’s current new construction energy code, the 2015 International Energy Conservation Code (IECC). The code packages were evaluated by

1. upfront cost impacts,

2. greenhouse gas (GHG) impacts over the lifetime of the building, and

3. operational energy cost impacts over the lifetime of the building.

The code packages investigated in this study included the 2021 IECC without amendments, the 2021 IECC with an electric-ready amendment, the 2021 IECC with an electric-preferred amendment, and the 2021 IECC with an all-electric amendment. These code options were analyzed for single-family homes, multi-family complexes, and commercial properties. The scope of work consisted of:

1. Upfront Cost Analysis: A literature review of existing studies analyzing the cost impacts of updating energy codes from prior code cycles, in this case, the 2015 and/or 2018 IECC, to the 2021 IECC. Additional studies were reviewed to understand the upfront cost impacts and cost-effectiveness of three additional above-building code standards, including electric-readiness, electric-preferred, and all-electric provisions.

2. Energy Modeling: Energy modeling for three building types typical of Eagle County construction: a single-family home, a multifamily building, and a mixed-use commercial building. Each building type was modeled to meet four code standards: the County’s current energy code (2015 IECC), the 2021 IECC, the 2021 IECC plus an electric-preferred standard, and the 2021 IECC with all-electric systems. The modeling was conducted to evaluate total annual energy consumption, total annual energy costs, and greenhouse gas emissions over the lifetime of the building (40-year period) to understand the emissions and cost implications of advancing to a new building code. The single-family and multifamily energy models were developed using the National Renewable Energy Laboratory’s Building Energy Optimization Tool. The commercial building energy model was developed using the Department of Energy’s eQUEST tool.

The upfront cost analysis and the energy modeling will demonstrate which code options are the most cost effective and which will have the greatest contribution to reducing greenhouse gas emissions in the County. In addition, Eagle County will be participating in a code cohort with surrounding jurisdictions to review and adopt supporting amendments alongside the 2021 I-codes. This effort will help advise Eagle County on which supporting amendments will support the achievement of their climate action goals through their next phase of energy code adoption.